Science... curtains!

Lesson: Science

We have been busy investigating the most suitable material for a pair of curtains. I'm sure Young Gru would have appreciated our help at the time, however, none of us were alive when he was Young... How old is Gru anyway!?

As a class, we concluded that the best material for a pair of curtains was felt. "It was very opaque indeed, Miss Harris!" said a keen scientist!